Northstar Engines and System Technical Discussion Discussion, Root Cause of Head gasket Failure and a Fix? in Cadillac Engine Technical Discussion; This is two of the head bolts. As you can see they have NO aluminum on them. I did not ...

Re: Root Cause of Head gasket Failure and a Fix?

GM will not warranty the Big Timesert or Norm's. GM states that if the bolt hole has erosion you can not TimeSert it and you must Replace the short block.
From my understanding all 1998 cars are now out of Warranty. With in a year all 1999 will be out they will not have any more 1999 and older Certified cars left under warranty.
.
.
.
.
JUMPPED POST AGAIN
.
.
.
I would never purchase a 96 to 99 Cadillac unless it was a 98 or 99 Seville and that maybe limited to a STS.
You can buy a 2002 or 2003 Seville for $6500 with 100K+ miles. A 99 Deville maybe worth $3k to $6K. Subtract the $3000 to $6000 for head gaskets and you have JUNK.
A 99 STS with 100K will go for $9000 now you can fix the car.

The reason I say up to $6000 in head gasket repairs is because of the cam shaft failure in the 93 to 99 models.

Re: Root Cause of Head gasket Failure and a Fix?

Very interesting writeup AJ, well done. My 98 SLS blew the gasket, but for a different reason than the one that you showed. The metal on my block was great, no pits or corrosion, hell the threads didn't even pull out, what killed mine were two gashes in the surface of the head, near the water jacket. I assume that they were a factory flaw from the factory, but I never did find the reason. In your estimation, since the block was in good shape, no powdered shavings, or pits, what are the chances of my 98 blowing a head gasket again?

Re: Root Cause of Head gasket Failure and a Fix?

YES
They maybe the OE supplier of that type of gasket for some engines. I am not sure about that, but some is making then for GM.

Originally Posted by JC316

Very interesting writeup AJ, well done. My 98 SLS blew the gasket, but for a different reason than the one that you showed. The metal on my block was great, no pits or corrosion, hell the threads didn't even pull out, what killed mine were two gashes in the surface of the head, near the water jacket. I assume that they were a factory flaw from the factory, but I never did find the reason. In your estimation, since the block was in good shape, no powdered shavings, or pits, what are the chances of my 98 blowing a head gasket again?

No pitting, No powder, No TimeSerts then the block should hold up just fine

Re: Root Cause of Head gasket Failure and a Fix?

My bad holes were very obviously different from my good holes. The good ones snapped really hard when they broke loose and the holes and bolts were dry. The bad ones were wet with coolant (I think). They was a slimy - and silvery coating - it was almost like anti-seize compound on the bolt threads. I think only one of them was completely stripped, but I drilled and inserted them all. I don't recall seeing any powdery aluminum - maybe I missed it.

I have given this a lot of thought, and I think (just a theory - just an opinion) the head gaskets let go first, allowed coolant & exhaust gases into the bolt holes and that degraded and corroded the aluminum to the point where the bolts let go, and the exhaust then entered the cooling system in a big way.

Re: Root Cause of Head gasket Failure and a Fix?

Originally Posted by JC316

I used the Timeserts on mine, they seemed to lock in nicely and I haven't seen a problem yet after 10,000 miles.

I have TimeSerted many thing over the years. On a Northstar Block the Drill/Ream is centered with a jig and then the drill goes down into the bore about 3" before it drills out the threads. This would mean that it is pretty well centered! Yeah right. The block was square at one time also. Do you understand that? OK the block goes through heat cycles and the bolt holes become slightly curved. When the drill gets to the bottom it drills ever so slightly off center. Maybe it goes towards the soft stuff. That would a good thing. Just think about this you have a drill in a 1" collar square to the deck and then it goes into a bore another 3". That means that it is held centered and square by a 4" tube. So why is it that I see so many off center? They hold up, but I just saying. So if one of the 20 hole is not perfect then the block is junk after the TimeSerts have been installed and they fail. If you just fix the bad ones and 75K later a different one fails you can fix the ones needed.